Tire Preparations 



Truck tire casing procurement and preparation presented a unique challenge 

 as truck tire casings are relatively scarce when compared with car tire casings. 

 Truck tires are also larger and much heavier to handle than car tires. Just as 

 a reminder, Figure 1 illustrates the difference in size between a typical large 

 truck tire and a medium size car tire (rim size at least 14 inches). One does 

 not need to work long with the truck tires before he gains real insight into why 

 a maze of these tires is a more effective absorber of wave energy. 



The rate of acquisition of truck tire casings did not meet expectations 

 while dealing directly with retailers in the area. The problem was eliminated 

 when personnel from Goodyear Research Division set up a working relationship 

 with one of its regional distributors. The distributor preselected casings and 

 arranged for pickup of tires over a wide area. This arrangement virtually 

 eliminated the need to return tires which were in excessively poor condition. 

 Pre-selection of the tires is an extremely important service as a significant 

 percentage of truck tire casings are torn up so badly on the interior that it 

 precludes their use. Truck tires tend to be run flat for longer distances 

 resulting in extreme ripping and tearing of the tire cords and, in some cases, 

 fusion and entanglement of the rubber inner tube onto a glob of rubber and cord 

 that can not be cut out in a reasonable time. At the time, the price charged to 

 dispose of a truck tire through an independent agent was approximately $1.50 per 

 casing due to the state's environmental restrictions. Obviously, this was an 

 expenditure to be avoided. 



Using a pneumatically driven punch, holes were punched in each tire casing 

 prior to inserting the foam components. The air compressor and punch were 

 loaned to the project by Goodyear Research Division. For steel-belted tires, 

 the holes were punched through the sidewall near the tread rather than directly 

 through the tread surface. Two holes of approximately 3/4-inch diameter were 

 punched in opposite ends of the casings (see Figure 2). These holes were used 

 as water drain holes for drying the casing prior to foaming. It is noted that 

 the foam agents will not cure properly in the presence of water; at the same 

 time, punching holes in the casing to drain the water insures that the tire will 

 be positively buoyant only if sufficient foam is applied to its interior. 

 Figure 3 shows an example of an adequately foamed steel belted tire. The foam 

 slug in this tire weighs approximately 3 lbs. Less foam is required for 

 smaller, non-steel-belted tires. 



Steel Tube Preparations 



Steel tubes 16 inch in diameter by 40 ft. in length with a wall thickness 



ranging from 1/4 to 5/16 inches were used in the breakwater assembly. Each tube 



was filled with cylindrically shaped foamed slugs approximately 2.5 to 3.0 ft. 



in length and having a diameter \/eY'y nearly equal to the pipe internal diameter. 



Molds for forming the foam slugs (Figure 4) were fabricated by rolling 

 sheet steel into a three-foot-long cylindrical shape. Two 3/4 by 3/4 inch right 

 angle steel bars were welded along the joining edges of each rolled sheet metal 

 tube. Standard hand vise grips applied to the edges of the welded bars firmly 

 closed the rolled sheet. The end profiles of the rolled sheet tubes were cut 

 from 2 ft. X 2 ft. x 3/4 inch sheets of plywood and slipped over both ends of 

 each cylinder to help stabilize the shape. Several molds of this type were 

 manufactured for use in the foaming operations. 



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